Introduction

FFmpeg is the universal multimedia toolkit: a complete, cross-platform solution to record, convert, filter and stream audio and video. It includes libavcodec - the leading audio/video codec library.

Google Summer of Code (GSoC) is a program that offers students stipends to write code for open source projects. Through the guidance of mentors, students gain valuable experience interacting with and coding for open source projects like FFmpeg. Additionally, the project and its users benefit from code created from students who often continue contributing as developers. FFmpeg participated to several past editions (2006, 2007, 2008, 2009, 2010, and 2011), and we are looking forward to being involved this year.

FFmpeg has not been accepted this year, so if you want to do any of the qualification tasks and projects, they are just for fun.

Information for Students

Getting Started

0. Get to know FFmpeg. If you are a student and interested in contributing to an FFmpeg GSoC project it is recommended to start by subscribing to the ffmpeg-devel mailing-list, visiting our IRC channels (#ffmpeg-devel and #ffmpeg), and exploring the codebase and the development workflow. Feel free to contact us if you have any questions.

1. Find a project. Listed on this page are mentored and unmentored projects. Mentored projects are well-defined and mentors have already volunteered. Unmentored projects are additional ideas that you may consider, but you will have to contact us to find a mentor. You may also propose your own project that may be a better match for your interest and skill level.

2. Contact us. If you find a project that you are interested in then get in touch with the community and let us know. In case you want to work on a qualification task, you should ask the appointed mentors so that the task can be claimed.

3. Apply. Student proposal period begins April 22, 2013 at 19:00 UTC and ends May 3rd at 19:00 UTC. See the GSoC timeline for additional information.

Qualification Tasks

In order to get accepted you will be requested to complete a small task in the area you want to contribute. FFmpeg GSoC projects can be challenging, and a qualification task will show us that you are motivated and have the potential to finish a project.

The qualification task is usually shown in the project description. Contact the appointed mentors for assistance on getting a related qualification task or if you want to propose your own. See a list of Small FFmpeg Tasks or browse the FFmpeg Bug Tracker for qualification task ideas.

Contacting FFmpeg

If you have questions or comments feel free to contact us via our mailing list, IRC channel, or e-mail one of the FFmpeg GSoC admins:

You can also contact a mentor directly if you have questions specifically related to one of the projects listed on this page.

Mentored Projects

This section lists well-defined projects that have one or more available mentors. If you are new to FFmpeg, and have relatively little experience with multimedia, you should favor a mentored project rather than propose your own. Contact the appointed mentor(s) to get more information about the project and the requested qualification task.

H.264 Multiview Video Coding (MVC)

Description: MVC samples exist and the codec is used on Blu-ray media, but FFmpeg is missing a decoder. Since this project also consists of some changes in the current architecture, it is especially important that this project is discussed on the ffmpeg-devel mailing list.

Misc Libavfilter extension

Description: Libavfilter is the FFmpeg filtering library. It currently supports audio and video filtering and generation support. This work may focus on porting, fixing, extending, or writing new audio and video filters from scratch.

Candidate filters for porting may be the remaining MPlayer filters currently supported through the mp wrapper, libaf MPlayer filters, and filters from other frameworks (e.g. mjpegtools, transcode, avisynth, virtualdub, etc.). In case of mp ports, the student should verify that the new filter produces the same output and is not slower.

Some ideas for more filters:

a frequency filtering domain filter relying on the FFT utils in libavcodec

a controller filter which allows to send commands to other filters (e.g. to adjust volume, contrast, etc.), e.g. like the sendcmd filter but through an interactive GUI

a lua scripting filter, which allows to implement filtering custom logic in lua

Subtitles

Description: FFmpeg has been working on improving its subtitles support recently, notably by adding the support for various text subtitles and various hardsubbing (burning the subtitles onto the video) facilities. While the theme may sound relatively simple compared to audio/video signal processing, the project carries an historical burden not easy to deal with, and introduces various issues very specific to its sparse form.

Expected results:

Add support for new subtitles formats. Example: a demuxer for .SUP files, just like VobSub but for Blu-Ray, or a VobSub muxer.

Improve text subtitles decoders. Typically, this can be supporting advanced markup features in SAMI or WebVTT.

Update the API to get rid of the clumsy internal text representation of styles

Proper integration of subtitles into libavfilter. This is the ultimate goal, as it will notably allow a complete subtitles rendering for applications such as ffplay.

BONUS: if everything goes well, the student will be allowed to add basic support for teletext

Prerequisites: C coding skills, familiarity with git/source code control systems. Some background in fansubbing area (notably ASS experience) would be a bonus but is not strictly required.

Qualification Task: write one subtitles demuxer and decoder (for example support for Spruce subtitles format). This is in order to make sure the subtitles chain is understood.

Postproc optimizations

Description: FFmpeg contains libpostproc, which is used to postprocess 8x8 DCT-MC based video and images (jpeg, mpeg-1/2/4, H.263 among others). The code though has been written a long time ago and its SIMD optimizations need to be updated to what modern CPUs support (AVX2 and SSE2+).

Expected results:

Convert all gcc inline asm in libpostproc to YASM.

Restructure the code so that it works with block sizes compatible with modern SIMD.

Add Integer SSE2 and AVX2 optimizations for each existing MMX/MMX2/3dnow optimization in libpostproc.

MPEG-4 ALS encoder

Description:
A MPEG-4 ALS decoder was implemented several years ago but an encoder is still missing in the official codebase. A rudimentary encoder has already been written and is available on github. For this project, that encoder is first to be updated to fit into the current codebase of FFmpeg and to be tested for conformance using the reference codec and specifications. Second, the encoder is to be brought through the usual reviewing process to hit the codebase at the end of the project.

Expected results:

Update the existing encoder to fit into the current codebase.

Ensure conformance of the encoder by verifying using the reference codec and generate a test case for FATE.

Ensure the FFmpeg decoder processes all generated files without warnings.

Enhance the rudimentary feature set of the encoder.

Prerequisites: C coding skills, familiarity with git/source code control systems. A certain interest in audio coding and/or knowledge about the FFmpeg codebase could be beneficial.

Hardware Acceleration (hwaccel) API v2

Description: FFmpeg supports hardware accelerated decoding through the internal hwacel API. Currently supported system hardware acceleration APIs are VA-API (Linux), DXVA2 (Windows) and VDA (MacOS X). However, the current approach requires client applications to allocate the underlying resources (e.g. hardware surfaces and context) themselves, and handing them over to FFmpeg. This incurs a few limitations: this is not scalable to new codecs, i.e. this requires new tokens for each newly supported codec; this incurs extra work in the client application, which tends to be duplicated over several client applications; and this prevents efficient fallback to software decoding mode if the hardware cannot handle a particular codec specification.

The goal of this project is to revamp the FFmpeg Hardware Acceleration API so that hardware resources are allocated and managed in the library, thus requiring the client application to only provide a single hardware context/device handle; provide a way to fallback early to software decoding mode if the underlying hardware won't be able to handle the bitstream; and make it possible to select a hardware accelerator by ID and not polluting the PixelFormats namespace.

Expected results:

FFmpeg core library (libavcodec):

Core API extensions and improvements

Add open/close hooks in a way that is backwards compatible with hwaccel v1 enabled applications

Add new tokens describing hardware accelerators

Add new flags exposing HW capabilities like download/upload

Investigate the benefits or impacts to provide a global map/unmap capability to FFmpeg video buffers

Port hwaccels to v2 infrastructure

Port VA-API decoders to v2 infrastructure

Validate that VA-API decoders still work with existing applications supporting hwaccel v1

Provide download capability through vaGetImage()

Validate that ffplay can support this feature with minor changes, and definitely no change to the existing SDL renderer

Hardware Accelerated Video Encoding with VA-API

Description: FFmpeg already supports hardware accelerated decoding for multiple codecs but still lacks support for hardware accelerated encoding. The aim of the project is to add support for encoding with VA-API specifically, while keeping a generic enough approach in mind so that other hardware accelerators (TI-DSP, CUDA?) could be supported as well. This means that new hwaccel hooks are needed and two operational modes are possible: either (i) driver or hardware pack headers themselves, or (ii) lattitude is left to perform this task at the FFmpeg library level.

AAC Improvements

Description: FFmpeg contains an AAC encoder and decoder, both of them can be improved in various ways. This is enough work for more than one GSoC project, so one part of your submission would be to define on which task exactly you want to work.

AAC LD decoder

AAC BSAC decoder: This has already been started, but the existing decoder still fails on many samples

AAC SSR decoder

AAC 960/120 MDCT window

AAC multi-channel encoding

Qualification Task: See the FFmpeg bug tracker for AAC issues, fixing one of them or rebasing the existing incomplete BSAC decoder for current git head or fixing one or more existing bugs are possible qualification tasks.

Prerequisites: C coding skills, familiarity with git/source code control systems, knowledge about transform based audio coding would be useful.

Unmentored Projects

This is a list of projects that students are encouraged to consider if a mentored project is unavailable or not within the students skill or interests. The student will have to find a mentor for the project. A student can also propose their own project.

glplay

Description: The SDL library that is used by FFplay has some deficiencies, adding OpenGL output to FFplay should allow for better performance (and less bugs at least for some hardware / driver combinations). This could be a new application (glplay), but it is probably simpler to extend ffplay to use OpenGL. You can use code from MPlayer's OpenGL vo module which may be relicensed under the LGPL.

Mentor: TBD Backup: Reimar Döffinger

TrueHD encoder

Description: FFmpeg currently does not support encoding to one of the lossless audio formats used on Bluray discs. This task consists of implementing a TrueHD encoder that allows to losslessly encode audio to play it on hardware devices capable of TrueHD decoding.

Opus decoder

Description: Opus decoding is currently supported through the external libopus library

Write a native decoder, continue working on the existing unfinished implementation

A possible qualification task is to port the existing incomplete decoder to current git head and improve it to show that you are capable of working on this task.

VC-1 interlaced

Description: The FFmpeg VC-1 decoder has improved over the years, but many samples are still not decoded bit-exact and real-world interlaced streams typically show artefacts.

Implement missing interlace features

Make more reference samples bit-exact

As a qualification task, you should try to find a bug in the current decoder implementation and fix it.

JPEG 2000

Description: FFmpeg contains an experimental native JPEG 2000 encoder and decoder. Both are missing many features, see also the FFmpeg bug tracker for some unsupported samples.
Work on an issue (for example from the bug tracker) as a qualification task to show that you are capable of improving the codec implementation.

VP7

Description: Not many VP7 samples are in the wild, but no open-source decoder exists although a specification exists. Write a decoder that reuses as much as possible of existing FFmpeg code: it is likely that functions of the existing decoders for On2-based formats will be useful.

VP8L

Description:VP8L is a lossless format used in WebP. There is no support for this in FFmpeg.

Your own idea

A student can propose a project. Ideas can also be found by browsing bugs and feature requests on our bug tracker. The work should last the majority of the GSoC duration, the task must be approved by the developers, and a mentor must be assigned.